The magical mermaid whirlpool is malfunctioning, but Naya and Marina are sucked in and transported to an underwater cave. Unable to return, they begin to explore and discover that they are in an underground river with many twists and turns. Their friends follow them in a rescue attempt, but they are all stuck there until they can figure out why the whirlpool is malfunctioning. One part of the underground river emerges in a sunlit jungle, and the merfriends have fun playing on the rocks. However, there is a dangerous predator lurking in the shadows of the jungle, and the mermaids will have to protect their vulnerable pets.

I loved this cute book! The mermaid culture is wonderfully imaginative, and I thought it was so fun to learn about all the mermaid friends. We also get some real life facts about interesting fish and conservation in the ocean. The plot and mysterious adventure had me guessing and wondering!

I love all the interesting mermaid characters. They all have their own strengths and that is what makes them such a great team. Coralie is funny and smart and strong. Naya is always inventing some type of new scientific magical combination to help them in their adventures. Luna has a special connection to marine animals. Kai is always looking for a new way to do things, a new approach to their problems. And Marina is the heart of the group, and she is always encouraging and supporting the others.

The black and white illustrations in this book are so cool! It really brings the story to life. I love the art style, and the unique designs for each mermaid character.

Disclaimer: I received a copy of this book from the publisher in exchange for a free and honest review. All the opinions stated here are my own true thoughts, and are not influenced by anyone.